Where can one see the border waiting time in real time or historical data, for people queuing from the US to Mexico?

Question

The US CBP provides a convenient online resource that gives the border waiting time in real time, for people queuing from Mexico/Canada to the US, either by car or by foot: https://bwt.cbp.gov/

Is there some online resource that gives the border waiting time in real time or historical data, for people queuing from the US to Mexico?

Google Maps is widely inaccurate. In response to a comment, yes there is sometimes a significant wait time from the US to Mexico by car even though there's no passport check, eg from a Friday at 6pm at San Ysidro (queue time=1h while Google maps was estimating 10 minutes. No accident, and almost all lanes at the border where one has to stop one's car momentarily were opened):

Answer 1

In California, Caltrans has a website with estimates of Autos Southbound Border Wait Times for the San Ysidro and Otay Mesa crossings.

BorderTraffic.com has webcams for many crossings. Some are free, while others involve a fee for access.

Answer 2

A few people on Reddit told me there exist Facebook groups dedicated to the border queuing times, but it's quite messy:

• https://www.facebook.com/groups/garitasdetijuana
• https://www.facebook.com/groups/155027725045343/
• https://www.facebook.com/groups/comoestalalineatijuana/
• https://www.facebook.com/comoestalalineatijuana/

Zach Lipton's pointer to Caltrans is likely better.